[clang] Add the flag -ffile-reproducible

When Clang generates the path prefix (i.e. the path of the directory
where the file is) when generating FILE, __builtin_FILE(), and
std::source_location, Clang uses the platform-specific path separator
character of the build environment where Clang _itself_ is built. This
leads to inconsistencies in Chrome builds where Clang running on
non-Windows environments uses the forward slash (/) path separator
while Clang running on Windows builds uses the backslash (\) path
separator. To fix this, we add a flag -ffile-reproducible (and its
inverse, -fno-file-reproducible) to have Clang use the target's
platform-specific file separator character.

Additionally, the existing flags -fmacro-prefix-map and
-ffile-prefix-map now both imply -ffile-reproducible. This can be
overriden by setting -fno-file-reproducible.

[0]: https://crbug.com/1310767

Differential revision: https://reviews.llvm.org/D122766

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/Basic/LangOptions.cpp b/clang/lib/Basic/LangOptions.cpp
index 2bc791c..7791bff 100644
--- a/clang/lib/Basic/LangOptions.cpp
+++ b/clang/lib/Basic/LangOptions.cpp
@@ -62,7 +62,7 @@ unsigned LangOptions::getOpenCLCompatibleVersion() const {
   llvm_unreachable("Unknown OpenCL version");
 }
 
-void LangOptions::remapPathPrefix(SmallString<256> &Path) const {
+void LangOptions::remapPathPrefix(SmallVectorImpl<char> &Path) const {
   for (const auto &Entry : MacroPrefixMap)
     if (llvm::sys::path::replace_path_prefix(Path, Entry.first, Entry.second))
       break;